Pfas-free thermoplastic multilayer fuel line

Abstract

A multilayer fuel line includes a liner layer, a barrier layer circumferentially surrounding the liner layer, and a cover layer circumferentially surrounding the barrier layer. The liner layer comprises polyterephthalamide and has an inner circumferential surface defining a tubular flowthrough passage extending in an axial direction through the multilayer fuel line. The inner circumferential surface of the liner layer has a surface resistivity of less than or equal to about 1×10 6 Ohms per square at 20 degrees Celsius. The barrier layer comprises ethylene vinyl alcohol. The cover layer defines an outer circumferential surface of the multilayer fuel line and comprises an aliphatic polyamide.

What is claimed is: 
     
         1 . A multilayer fuel line comprising:
 a liner layer having an inner circumferential surface defining a tubular flowthrough passage extending in an axial direction through the multilayer fuel line, the liner layer comprising polyterephthalamide, the inner circumferential surface of the liner layer having a surface resistivity of less than or equal to about 1×10 6  Ohms per square at 20 degrees Celsius;   a barrier layer circumferentially surrounding the liner layer, the barrier layer comprising ethylene vinyl alcohol; and   a cover layer circumferentially surrounding the barrier layer and defining an outer circumferential surface of the multilayer fuel line, the cover layer comprising an aliphatic polyamide.   
     
     
         2 . The multilayer fuel line of  claim 1 , wherein the liner layer comprises poly(nonamethylene terephthalamide). 
     
     
         3 . The multilayer fuel line of  claim 1 , wherein the liner layer is substantially free of esters and amides having molecular weights of less than or equal to about 2000. 
     
     
         4 . The multilayer fuel line of  claim 1 , wherein the liner layer comprises:
 a continuous matrix phase; and   a dispersed phase distributed throughout the continuous matrix phase,   wherein the continuous matrix phase comprises the polyterephthalamide and the dispersed phase comprises an electrically conductive agent.   
     
     
         5 . The multilayer fuel line of  claim 4 , wherein the electrically conductive agent comprises carbon. 
     
     
         6 . The multilayer fuel line of  claim 4 , wherein the continuous matrix phase constitutes, by weight, greater than or equal to about 80% to less than or equal to about 99.8% of the liner layer, and wherein the electrically conductive agent constitutes, by weight, greater than or equal to about 0.2% to less than or equal to about 20% of the liner layer. 
     
     
         7 . The multilayer fuel line of  claim 1 , wherein the liner layer comprises:
 an electrically conductive inner layer defining the inner circumferential surface of the liner layer and comprising a continuous matrix phase comprising polyterephthalamide and a dispersed phase comprising an electrically conductive agent; and   an electrically insulating outer layer circumferentially surrounding the inner layer, the electrically insulating outer layer comprising polyterephthalamide and having a surface resistivity of greater than 1×10 6  Ohms per square at 20 degrees Celsius.   
     
     
         8 . The multilayer fuel line of  claim 1 , further comprising:
 an intermediate layer circumferentially surrounding the liner layer and being disposed between the liner layer and the barrier layer, the intermediate layer comprising an aliphatic polyamide.   
     
     
         9 . The multilayer fuel line of  claim 8 , wherein the intermediate layer comprises poly(dodecano-12-lactam). 
     
     
         10 . The multilayer fuel line of  claim 8 , wherein the intermediate layer is directly physically and chemically bonded to the liner layer without use of an adhesive. 
     
     
         11 . The multilayer fuel line of  claim 1 , wherein the barrier layer creates a seal around the tubular flowthrough passage that prevents fuel vapors from permeating through the multilayer fuel line and escaping to an external ambient environment. 
     
     
         12 . The multilayer fuel line of  claim 1 , wherein the cover layer comprises poly(dodecano-12-lactam), poly(hexamethylene dodecanediamide), or a combination thereof. 
     
     
         13 . The multilayer fuel line of  claim 1 , wherein the multilayer fuel line is substantially free of perfluoroalkyl substances, polyfluoroalkyl substances, and combinations thereof. 
     
     
         14 . The multilayer fuel line of  claim 1 , further comprising:
 a first adhesive layer disposed between the liner layer and the barrier layer that physically bonds the barrier layer to the liner layer; and   a second adhesive layer disposed between the barrier layer and the cover layer that physically bonds the cover layer to the barrier layer,   wherein the first and second adhesive layers each comprise a thermoplastic polymer.   
     
     
         15 . The multilayer fuel line of  claim 1 , wherein the multilayer fuel line is configured to withstand temperatures in a range of greater than or equal to about-40 degrees Celsius to less than or equal to about 130 degrees Celsius. 
     
     
         16 . A multilayer fuel line comprising:
 a liner layer having an inner circumferential surface defining a tubular flowthrough passage extending in an axial direction through the multilayer fuel line;   an intermediate layer circumferentially surrounding the liner layer, the intermediate layer comprising an aliphatic polyamide;   a barrier layer circumferentially surrounding the intermediate layer, the barrier layer comprising ethylene vinyl alcohol; and   a cover layer circumferentially surrounding the barrier layer and defining an outer circumferential surface of the multilayer fuel line, the cover layer comprising an aliphatic polyamide,   wherein the liner layer has a composite structure comprising a continuous matrix phase and a dispersed phase distributed throughout the continuous matrix phase,   wherein the continuous matrix phase comprises poly(nonamethylene terephthalamide) and the dispersed phase comprises an electrically conductive agent, and   wherein the electrically conductive agent provides the inner circumferential surface of the liner layer with a surface resistivity of less than or equal to about 1×10 6  Ohms per square at 20 degrees Celsius.   
     
     
         17 . The multilayer fuel line of  claim 16 , wherein the poly(nonamethylene terephthalamide) of the liner layer provides the inner circumferential surface of the liner layer with chemical resistance and low oligomer extraction against volatile liquid fuels. 
     
     
         18 . The multilayer fuel line of  claim 16 , wherein the barrier layer creates a seal that circumferentially surrounds the tubular flowthrough passage and prevents fuel vapors from permeating through the multilayer fuel line and escaping to an external ambient environment. 
     
     
         19 . The multilayer fuel line of  claim 16 , wherein the intermediate layer, the barrier layer, and the cover layer are electrically insulating and have surface resistivities of greater than 1×10 6  Ohms per square at 20 degrees Celsius. 
     
     
         20 . The multilayer fuel line of  claim 16 , wherein the multilayer fuel line is substantially free of perfluoroalkyl substances, polyfluoroalkyl substances, and combinations thereof, and wherein the multilayer fuel line is configured to withstand temperatures in a range of greater than or equal to about −40 degrees Celsius to less than or equal to about 130 degrees Celsius.